Protecting premises against unauthorized entry by criminals is commonly achieved using fixed metal (usually steel or aluminum) burglar bars secured over windows as well as laterally collapsible latticed intruder barriers over doorways.
As regards windows, the windows themselves are commonly alarmed by way of magnetic switches that detect when a window is opened by virtue of the switch changing from an open to a close condition or vice versa, according to the type of alarm system that is employed.
The existing common arrangement has at least two main disadvantages, namely, the metal burglar bars are generally unsightly and impair the view through the window, and secondly there is generally no means of warning if a burglar bar has been cut or is otherwise tampered with whilst a window has been left open with the alarm inoperative by virtue of it being switched off to allow the window to be opened.
U.S. Pat. No. 3,947,837 has suggested a glass panel having an electrical conductor embedded therein such that an alarm can be triggered if the glass is broken. However, such an arrangement offers no protection whatsoever whilst the relevant window is left open and metal burglar bars would nevertheless need to be employed if a window is to be left open.
Applicant is unaware of any burglar alarms that have been integrated into a laterally collapsible latticed intruder barrier that is also unsightly and impairs the view through a doorway or window being protected.